I have a long trip to take and my rear diff is kinda noisy. It was all rebuilt about 30k miles ago. Its a 1 ton van, I believe Chrysler rear end. Anyway, Is it okay to use Lucas in a rear diff? I used it in an engine and it foamed terrible. I know these kinds of threads can take off with repair or replace, but that is not an option at this time. If lucas isnt good , is there something I can use ? It's not howling or screaming , just has an audible whine about 70 mph

 

Nope, Lucas oil stabilizer is true junk that should not be put into anything the owner cares about.

If taking off the diff cover, one can try a boutique gear oil like Redline or AMSoil.

I'd try a high Moly oil in an open differential, but not a limited slip.

Lubro/liqui Moly make good products.

I plan on adding this to my mobil 1 75w/90, right before I go on the next road trip where the diff will get nearly as hot as it gets.


Schaffers and Swepco make high Moly gear oils. Lots of gear oils have no Moly because it is a friction modifier that will mess with the function of limited slip differentials.

http://www.schaefferoil.com/full-synthetic-lube.html

If my current gear oil was due to be replaced, I'd definitely go with the Schaffers #167.

It is asking a lot for a lubricant alone to change the noise of a differential, and much of the noise that is often attributed to the Diff can be tires or universal joints as the Van body makes it difficult to discern where a noise originates.